In the past, safety pocket knives have been provided which slide in a handle and are adapted to have control means associated therewith to facilitate opening and closing of the handle to allow the blade to shift from one position to another as shown in U.S. Pat. No. 475,306. The blade in the pocket knife of the referenced patent is provided with spring jaws or a pawl, which are adapted to be actuated by a push rod.
In U.S. Pat. No. 515,743, the pocket knife is provided with a finger piece to hold the blade in position. In U.S. Pat. No. 1,024,749, a removable pin is employed to engage the back of the blade to prevent the blade from coming back. U.S. Pat. No. 1,453,897 employs a tubular casing, a bar adapted to co-act with a cam upon manipulation of the bar longitudinally of the casing to expose or retract the blade.
In U.S. Pat. No. 1,859,158, a pair of blades are provided which can be adoptably held in different positions.
In recent U.S. Pat. No. 4,926,555, a button is pivotally connected to the rearward end of the blade and is adapted to be pushed on or twisted to release a blade wherefore the same is sunk into the blade.
The prior art presents differences over the present invention and said disclosures either require the use of both hands and none are self-locking.